Venom peptide repertoire of the European myrmicine ant Manica rubida: identification of insecticidal toxins.

Using an integrated transcriptomic and proteomic approach, we characterized the venom peptidome of the European red ant, Manica rubida. We identified 13 "myrmicitoxins" that share sequence similarities with previously identified ant venom peptides, one of them being identified as an EGF-like toxin likely resulting from a threonine residue modified by O-fucosylation. Furthermore, we conducted insecticidal assays of reversed-phase HPLC venom fractions on the blowfly Lucilia caesar, permitting us to identify six myrmicitoxins (i.e., U-3-, U-10-, U-13-, U-20-MYRTX-Mrila, U-10-MYRTX-Mrilb, and U-10-MYRTX-Mril c) with an insecticidal activity. Chemically synthesized U-10-MYRTX-Mrila, -Mrilb, -Mrilc, and U-20-MYRTX-Mrila irreversibly paralyzed blowflies at the highest doses tested (30-125 nmol.g(-)(1)). U-13-MYRTX-Mrila, the most potent neurotoxic peptide at 1 h, had reversible effects after 24 h (150 nmol.g(-)(1)). Finally, U-3-MYRTX-Mri la has no insecticidal activity, even at up to 55 nmol.g(-1). Thus, M. rubida employs a paralytic venom rich in linear insecticidal peptides, which likely act by disrupting cell membranes.